High strength steel

Ordinary high strength steel plate

High strength IF steel plate: make the steel in the guarantee of good plasticity and stamping performance, at the same time, have high strength, meet the performance requirements of complex shape car stamping parts.

Baking hardened steel plate (BH steel) : The steel plate has a low yield strength before stamping, and the yield strength of the steel plate is increased by the paint baking process after stamping.

Phosphorous steel plate: using phosphorous in steel solution strengthening action to strengthen, can be used to punch some more complex shape of automobile stamping parts.

Ultra-low carbon phosphorus steel plate: This steel has good deep drawing, plasticity and toughness.

Isotropic steel plate (IS steel) : mainly used for automobile exterior plate.

Advanced High Strength Steel Sheet (AHSS)

Dual-Phase (referred to as DP) steel: generally used for high strength, high anti-collision absorption energy and forming requirements are also more stringent automotive parts, such as wheels, bumpers, suspension system and its reinforcement, with the progress of steel performance and forming technology, DP steel is also used in the car inside and outside the plate and other parts.

Bainite steel plate: suitable for stamping auto support parts, which are thick and require good flanging performance.

Transformation induced plasticity steel (TransformationInducedPlastic TRIP) : especially suitable for requirements with high expansion.

ComplexPhase (CP) steel: with high absorption energy and good reaming performance, it is especially suitable for safety parts such as door crash bars, bumpers and B columns.

Martensitic steel: It is the highest strength grade of commercial high strength steel plate. It is mainly used to replace tubular parts for car door collision bar and other parts with low molding requirements to reduce manufacturing costs.

Coated steel plate

Performance requirements for coated steel plates in the automotive industry

In the process of automobile manufacturing, coated steel plate should go through stamping forming, welding, surface treatment, painting and baking processes, so the automobile industry has the following performance requirements for coated steel plate:

1), formability: the substrate is suitable for molding requirements, coating adhesion, anti peeling, anti powder;

2) Corrosion resistance: resistance to winter road salt corrosion, resistance to oceanic climate and atmospheric corrosion;

3), paint: phosphating and electrophoresis coating performance is good;

4), weldability: the electrode damage is small, welding parameters range is wide;

5) Surface quality: flat surface, uniform coating thickness;

6), tolerance size: flat shape, small tolerance.

The main varieties of coated steel plate for automobile

Automobile body used in various types of plating plate, mainly including hot dip galvanized (hot dip galvanized GI, alloying hot dip galvanized GA, etc.) steel plate, electric galvanized (plating pure zinc, electric galvanized nickel alloy and alloying electric galvanized, etc.) steel plate and organic, inorganic coating steel plate.

Cold rolling and hot rolling concepts

1. Hot rolled

The continuous casting slab or the first rolled slab is used as raw material, which is heated by a stepping furnace and dephosphorized by high pressure water, and then enters the roughing mill. The roughing material enters the finishing mill after cutting head, tail and then enters the finishing mill to implement computer-controlled rolling. After the final rolling, it passes through laminar cooling (computer-controlled cooling rate) and coiling machine to become a straight roll. The head and tail of straight hair roll are often tongue and fish tail, the thickness and width accuracy is poor, and the edge often has wave shape, hem, tower shape and other defects. The coil weight is heavier and the inner diameter of the steel coil is 760mm. (The general pipe industry likes to use.) After finishing the straight hair coil by cutting the head, cutting the tail, cutting the edge, straightening and leveling several times, then cutting the plate or rewinding, it becomes: hot rolled steel plate, flat hot rolled steel coil, slitting strip and other products. The hot rolled pickling plate roll is formed after removing the oxide skin by pickling and applying oil.

2. The cold rolling

The HOT rolled steel coil is used as raw material, the oxide skin is removed by pickling, and the finished product is rolled hard coil. The cold work hardening caused by continuous cold deformation increases the strength and hardness of rolled hard coil, decreases the toughness and plastic index, and deteriorates the stamping performance, so it can only be used for simple deformed parts. Hard rolling coil can be used as raw material for hot dip galvanizing plant because hot dip galvanizing units are equipped with annealing line. The rolling coil weight is generally 6~13.5 tons, and the inner diameter of the steel coil is 610mm. In order to eliminate cold working hardening and rolling STRESS and reach THE mechanical properties SPECIFIED in the STANDARD, the plate and reel should be annealed by continuous annealing (CAPL unit) or hood furnace. The surface quality, appearance and dimensional accuracy of cold rolled steel plate are better than those of hot rolled steel plate.

t is rolled hard coil. The cold work hardening caused by continuous cold deformation increases the strength and hardness of rolled hard coil, decreases the toughness and plastic index, and deteriorates the stamping performance, so it can only be used for simple deformed parts. Hard rolling coil can be used as raw material for hot dip galvanizing plant because hot dip galvanizing units are equipped with annealing line. The rolling coil weight is generally 6~13.5 tons, and the inner diameter of the steel coil is 610mm. In order to eliminate cold working hardening and rolling STRESS and reach THE mechanical properties SPECIFIED in the STANDARD, the plate and reel should be annealed by continuous annealing (CAPL unit) or hood furnace. The surface quality, appearance and dimensional accuracy of cold rolled steel plate are better than those of hot rolled steel plate.